Download Ch 3 – Biological Bases of Behavior

Biological Bases of Behavior
AP Psych – Chapter 3
Biological Foundations of Behavior
Alice F. Short
Hilliard Davidson High School
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Nervous System
Neurons
Brain
Endocrine System
Damage, Plasticity, and Repair
Genetics and Behavior
Biological Foundations and Health and
Wellness
Nervous System
• neuroscience - study of the body’s
electrochemical communication circuitry
• characteristics of the nervous system
– complexity
• (metaphor = multitasking)
– integration
– adaptability (plasticity)
– electrochemical transmission
Nervous System: Pathways
• Afferent Nerves (in)
– carry information  spinal cord and brain
• Efferent Nerves (exit)
– carry information  muscles
The Two Main Divisions of the Nervous System:
• 1. Central Nervous System (CNS)
– brain and spinal cord
• 2. Peripheral Nervous System (PNS)
– somatic nervous system – sensory nerves
• muscular activity
– autonomic nervous system – internal organs
• sympathetic nervous system – arouses
• parasympathetic nervous system – calms
Nervous
System:
Divisions
1. Central Nervous System
• 1. Central Nervous System (CNS)
– brain and spinal cord
2. Peripheral Nervous System
• 2. Peripheral Nervous System (PNS) – composed of all
the sensory and motor nerves
– somatic nervous system (voluntary) – sensory nerves
• carries info to muscles  muscular activity
– allows you to move in cases of emergency
– allows you to move when you want to move
– “instruct” “tell” “decide” to move muscles
– autonomic nervous system (involuntary) – internal organs
• carries information to and from internal organs
• monitors breathing, heart rate, digestion
• sympathetic nervous system – arouses
– kicks into overdrive in cases of emergency (“fight or flight”)
– neurotransmitter: noradrenaline
• parasympathetic nervous system – calms
– medication techniques elicit response
– neurotransmitter: acetocholine
Nervous System: 2 Types of Cells
• neurons
– basic unit of the nervous system
– information processing
– part of neuron: dendrites, cell body (soma), axon,
myelin sheath, axon terminals, terminal buttons,
nucleus
– mirror neurons (in primates) – imitating behaviors of
someone else
• mimicking the movements of a coach or dancer, etc.
• glial cells
– provide support and nutrition
– carries nutrients from blood vessels  neurons
Neurons: Structure
• neuron – the type of cell that is the basic unit of
the nervous system – the nervous system
contains over 11 billion neurons
1. cell body (soma) – contains the nucleus
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directs the manufacture of substances that the neuron
needs for growth and maintenance
2. dendrites – branched appendages that carry
information to the cell body (receives info)
3. axon – conveys information away from the cell body
toward other cells
4. myelin sheath – layer of fat, covers the axon and aids
in neural transmission (faster and smoother
transmission)
Neurons: Structure
• dendrite  cell body  axon
Neurons: 3 Types
Neuron – the type of cell that is the basic unit of the nervous
system – the nervous system contains over 11 billion
neurons
1. sensory neurons are located in the body’s sense organs
(for example, the eye, ear, or nose) and send information
from these organs to the brain
2. motor neurons– convey information from the nervous
system to the body’s organs, glands, and muscles
3. interneurons (association neurons) transmit information
from one neuron to another within the nervous system
• Axons
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ions/ion channel
negatively/positively charged
semipermeable membrane
polarization
Neural
Impulse
• Resting Potential
– stable charge of an inactive neuron
– a negative charge on the inside of the cell membrane and a
positive charge on the outside
• Action Potential
– depolarization (ion channel opens)
• sodium ions flow into the membrane
– repolarization
– ion exchange sweeps along length of axon
• a brief wave of positive and electrical charge that sweeps down the axon
– all-or-none principle – intensity of the action potential is not
effected by depolarizing and greater levels
– once initiated, cannot be stopped
Transmission of Nerve Impulse
Synapses and Neurotransmitters
• Synapse / Synaptic Gap
– space between sending axon’s terminal buttons and
the receiving dendrite or cell body
– the neural message being delivered in a synaptic
transmission is carried across the synaptic gap by
chemical substances
• Synaptic Transmission
– electrical impulse is converted into a chemical signal
– axon vesicle releases neurotransmitter into gap
– dendrite receptor site detects neurotransmitter
Synapses and Neurotransmitters
© 2011 The McGraw-Hill Companies, Inc.
Neurotransmitters
• Neurotransmitters carry information across the synaptic
gap to next neuron. (chemical)
– Acetylcholine
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muscle actions, learning, memory
black widow venom ↑ Ach levels
botox (botulin) ↓ Ach levels
Alzheimer’s disease: ↓ Ach levels
– GABA
• anxiety: ↓ GABA levels
– Glutamate
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excitatory
learning & memory
involved in many psychological disorders
↑ causes migraines
– Norepinephrine
• stress and mania: ↑ norepinephrine levels
• depression: ↓ norepinephrine levels
• regulates sleep states in conjunction with ACh
Neurotransmitters (cont.)
• Dopamine
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voluntary movement
reward anticipation
stimulant drugs: activate dopamine receptors
Parkinson’s disease: ↓ dopamine levels
schizophrenia: ↑ dopamine levels
• Serotonin
– regulation of sleep, mood, attention, learning
– depression: ↓ serotonin levels
– prozac: ↑ serotonin levels
• Endorphins
– natural opiates
– mediate feelings of pleasure and pain
• Oxytocin
– both a hormone and a neurotransmitter
– related to onset of lactation in new mothers
– related to attachment/emotional bonds
Neurotransmitters
• Note: Drugs can interfere with
neurotransmitters
– mimics or enhances NT effects
– blocks effects of NT
Neural Networks
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interconnected pathways of nerve cells
integrate sensory input and motor output
take years to develop
a given piece of information embedded in
multiple connections between neurons
Studying the Brain
• Brain Lesioning
– naturally occurring or induced
• Electrical Recording
– electroencephalograph (EEG)
– single-unit recording
Brain Imaging
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X-Ray
CT Scan
PET
MRI
fMRI
TMS
Brain Imaging: X- Ray
• X-Ray
– reveals damage in body
– brain and other locations
– shows a 2-dimensional image
– poses problem of radiation overexposure
Brain Imaging: CAT/CT Scan
• computerized axial tomography - CAT/CT Scan
– improved imaging from X-Ray
– produces a 3-dimensional image of X-rays
– assembled into a composite image on computer
– provide info on location and extent of damage
– used for language disorder, damage in stroke, loss
of memory
Brain Imaging: PET Scan
• positron-emission tomography – PET Scan
– based on metabolic changes in the brain related
to activity
– measures amount of glucose in various areas of
the brain
• neurons use glucose for energy  glucose levels vary
based on level of activity
– Stephen Kosslyn (1996)
• Area 17
Brain Imaging: MRI
• magnetic resonance imaging – MRI
– creates a magnetic field around a person body
• 50,000 times more powerful than the earth’s magnetic field
– uses radio waves to construct images of the person’s
tissues and biochemical activities
– uses magnetic properties in the hydrogen atoms of water
(people = 70% water)
– generates clear pictures of brain’s interior
– does not require injecting the brain with a substance
– does not pose a proem of radiation overexposure
– reclining in a large metal barrel
– portrays structure, NOT function
Brain Imaging: fMRI
• functional magnetic resonance imaging - fMRI
– allows scientists to se what is happening in the brain
while it is happening
– rests on the idea that mental activity is associated with
changes in the brain
– uses changes in blood oxygen that occur in association
with brain activity
• oxygenated blood rushes to area—don’t use all of it
– reclining in a large metal barrel – and doing something
• comparison: at rest vs. listening to music brain activity
• tells specific brain activity associated with mental experience
– association (a correlation statement – not a causal statement)
– cognitive neuroscience – field which involves linking
cognitive processes and their underlying neural bases
Brain Imaging: TMS
• transcranial magnetic stimulation - TMS
– often combined with brain-imaging techniques to
establish causal links between brain activity and
behavior
– places magnetic coils over a person’s head and
directed at a particular brain area
– uses rapidly changing magnetic field to induce brief
electric current pulses in the brain  triggers action
potentials in neurons  following this burst of action
potential, activity in the targeted brain area is
inhibited, causing a virtual lesion
• temporary disruption should disrupt behavior as well
Areas of the Brain
1. Hindbrain
2. Midbrain
3. forebrain
Reminder: any part of the brain is a part of the
central nervous system (CNS), which is a part
of the nervous system in general
Areas of the Brain: 1. Hindbrain
• Brainstem
– medulla –
control
breathing,
regulate
reflexes
– pons – sleep
& arousal
• Cerebellum
– motor
coordination
Areas of the Brain: 1. Hindbrain
• Brainstem
– medulla
• controls breathing and heart rate
• regulates reflexes
• begins where the spinal cord enters the skull
– pons –
• contains several clusters of fibers
– involved in sleep & arousal
• connects the cerebellum and the brain stem
• Cerebellum
– motor coordination
Areas of the Brain:
2. Midbrain
• midbrain
– located between the hindbrain and
forebrain
– area in which many nerve-fiber
systems ascend and descend to
connect the higher and lower
portions of the brain
• relays info between brain, eyes and
ears
– substantia nigra
• near the bottom of the midbrain
• damage: Parkinson disease
– deterioration in body movement,
rigidity and tremors
• contains dopamine-producing neurons
 feeds dopamine into striatum
– striatum
• central inputs station of basal ganglia
– reticular formation
• stereotyped behavior patterns like
walking, sleeping, turning to attend to
a sudden noise
• manipulates neurotransmitters
Brain: Structure and Function
Areas of the Brain: 3. Forebrain
• forebrain (brain’s largest division and its most forward part)
– limbic system – loosely connected network of structures under the cerebral
cortex
• memory and emotion (including intense emotions)
• amygdala – almond-shaped structure located inside the brain toward the base (one on
each side of the brain)
– discrimination of objects needed for survival (appropriate food, mates, and social rivals)
– emotional awareness and expression
– lesions: incorrect actions (example: trying to eat, fight with or mate with a chair); inability to
recognize facial expressions
• hippocampus
– formation and recall of memories
– damage: cannot retain new memories
– memories: help choose WHERE to store, and helps retrieval… does not actually store memories
– thalamus (sits at the top of the brain stem)
• relay station for much sensory information
– basal ganglia (above the thalamus and under the cerebral cortex)
• coordination of voluntary movements; habitual activities
• ganglia – large clusters of neurons
• damage: unwanted movement (jerking/writhing OR too slow of movement)
– hypothalamus (just below the thalamus) (see next slide)
– cerebral cortex (see next slide)
Areas of the Brain: 3. Forebrain
• forebrain (brain’s largest division and its most forward part)
– limbic system
• amygdala
• hippocampus
– thalamus
– basal ganglia
– hypothalamus (just below the thalamus)
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eating, drinking, sexual behaviors
regulate body’s internal state
emotion, stress, reward
helps direct the endocrine system  influence pituitary gland
sensitive to changes in the blood and neural input influences the
secretion of hormones and neural inputs
• James Olds and Peter Milner (1954)
– rats: planted electrode in hypothalamus (mild electric current when rat wend to
corner)  rats “pleasured self” to death
– cerebral cortex (see next slide)
Areas of the Brain 3. Forebrain:
Cerebral Cortex
• Neocortex: outermost layer
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cortex = bark in Latin; neocortex = “new bark”
80% of cortex (30-40% in other mammals)
“wrinkling” increasing surface area
responsible for high-level thinking
• Four Lobes:
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occipital (vision)
temporal (hearing, language processing, memory)
frontal (intelligence, personality, voluntary muscles)
parietal (spatial location, attention, motor control)
Cerebral Cortex
• Four Lobes:
– occipital (vision)
– temporal (hearing, language
processing, memory)
• connections to limbic system
• damage: cannot file info into longterm memory
• face recognition?
– frontal (intelligence, personality,
voluntary muscles)
• Phineas T. Gage
• prefrontal cortex – the front of the
motor cortex
– involved in higher functions such as
planning, reasoning and self-control
• motor cortex
– parietal (spatial location, attention,
motor control)
• somatosensory cortex
• Albert Einstein: 15% larger than
average
– WARNING: don’t over generalize…
the brain is complex
Are Brains Wired to Recognize Faces?
• prosopagnosia
– inability to recognize faces
• fusiform face area (FFA)
– FFA – specifically for processing faces?
• DISCUSSION: Critical Controversy on p. 78
Cerebral Cortex: Somatosensory,
Motor Cortex, and Association Cortex
• somatosensoy cortex (in parietal lobe at front)
– body sensations
• motor cortex (in frontal lobe at rear)
– voluntary movements
• point-to-point mapping
– relationship between point of body and point on cerebral cortex
• association cortex / association areas (75% of cortex)
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not sensory or motor, but associations between
integrates sensory and motor information
embedded in the brain’s lobes
thinking and problem solving
specific areas for language – can be damaged
other areas less critical (more a matter of degree of damage)
Split-Brain
Research
• Corpus Callosum
– large bundle of axons that
connects the two hemispheres of
the brain
– relays information between the two
hemispheres
• Roger Sperry (1974)
– W.J., the Split Brain Patient (terrible
seizures)
Hemispheric Specialization of Function
• left hemisphere
– verbal processing, speech, grammar (most, not all)
• Broca’s Area – left hemisphere
– production of speech
– Paul Broca – “Tan”
– expressive aphasia/Broca’s aphasia – a language disorder that involves
the inability to produce language
• Wernicke’s Area – left hemisphere
– comprehending language
– Carl Wernicke
• right hemisphere
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spatial perception, visual recognition, emotion
intonations of voices
song melodies
sense of humor
Hemispheres of
the Cortex
INTERSECTION: Happy Brains
p. 84
• Happiness: Prefrontal Lobe Asymmetry
– positive emotional responses
• more left prefrontal lobe activity
– negative emotional responses
• more right prefrontal lobe activity
• Biofeedback
• Mindfulness (Awareness) Meditation
Endocrine System
• set of glands that regulate the body by secreting
hormones into the bloodstream
– glands – organs or tissues in the body that create
chemicals that control many of our bodily functions
– hormones = chemical messages
– relatively slow communication system
– interconnected with the nervous system
• pituitary, thyroid, parathyroid, adrenal glands,
pancreas, ovaries, testes
Endocrine System
• pituitary gland – a pea-sized gland just beneath the hypothalamus that
controls growth and regulates other glands
• adrenal gland – glands at the top of each kidney that are responsible for
regulating moods, energy level, and the ability to cope with stress
– epinephrine / adrenaline
– norepinephrine / noradrenaline -
• pancreas – a dual-purpose gland under the stomach that performs both
digestive and endocrine functions
– Islets of Langerhans – little hormone factory
• produces the hormone insulin – regulates glucose (blood sugar) levels (controls
metabolism, body weight and obesity
• ovaries – sex-related endocrine glands in the uterus that produce
hormones related to women’s sexual development and reproduction
• testes – sex-related endocrine glands in the scrotum that produce
hormones related to men’s sexual development and reproduction
• nervous system and endocrine system = intricately interconnected
(hypothalamus)
Brain Damage and Plasticity
• Recovery from brain damage depends on
– age of the individual
– extent of the damage
• Repairing the damaged brain
– collateral sprouting – process by which axons of some healthy
neurons adjacent to damaged cells grow new branches
– substitution of function – process by which the damaged
region’s function is taken over by another area or areas of the
brain
– neurogenesis - process by which new neurons are generated
• humans: only documented in hippocampus and olfactory bulb
• exercise increase neurogenesis
– brain tissue grafts – implants of healthy tissue into damaged
brains
• most successful at the fetal stage
– stem cells – unique primitive cells that have the capacity to
develop into most types of human cells
• CONTROVERSIAL: harvest of frozen embryos left-over from in vitro
fertilization (Where to do you stand on the issue? Why?)
Genetics and Behavior
• chromosomes, genes, and DNA
– chromosomes – in the human cell, threadlike
structures that come in 23 pairs, one member of each
pair originating from each parent, and that contain a
remarkable about of DNA
– deoxyribonucleic acid (DNA) – a complex molecule in
the cell’s chromosomes that carries genetic
information
– genes – the units of hereditary information consisting
of short segments of chromosomes composed of DNA
• hold the code for creating proteins called amino acids that
forms the bases for everything our bodies do
Genetics and Behavior
• Human Genome Project
– genome – an organism’s complete genetic material
– human beings: approx. 20,500 genes
• dominant-recessive genes principle – if one gene of a
pair is dominant and one is recessive, the dominant
gene overrides the recessive gene – a recessive gene
exerts its influence only if both genes of a pair are
recessive
– polygenic inheritance – the influences of multiple genes
on behavior
• molecular genetics – the manipulation of genes using
technology to determine their effect on behavior
– ADVANCES: knowing diseases, etc.
Genetics and Behavior
• selective breeding – a genetic method in
which organisms are chosen for reproduction
based on how much of a particular trait they
display
– Gregor Mendel and pea plants
– Robert Tryon (1940) – maze-smart rats (21
generations) – see p. 89
– eugenics – the application of selective breading to
humans (espoused by Adolf Hitler)
Genetics and Behavior
• behavior genetics and adoption studies
– behavior genetics – the study of the degree and
nature of heredity’s influence on behavior
• identical twins – develop from a single fertilized egg
that splits into two genetically identical embryos
• fraternal twins – develop from separate eggs and
separate sperm
• twin study (Italy)
– self-esteem, life satisfaction, optimism for the future
– genetic tendency to have a positive attitude
– environment = greater influence on self-esteem
• Minnesota Twin Study – p. 90
Genes and the Environment
• genotype – genetic heritage
+ the effects of experience =
• phenotype – observable characteristics
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environment alters how genetic traits develop
both physical & psychological characteristics
genetic expression
applies to both physical and psychological
characteristics
• genetic expression – refers to gene activity that
affects the body’s cells, is influenced by the
gene’s environment
Biological Foundations
and Health and Wellness
• stressors
– circumstances and events that threaten individuals and/or
tax their coping abilities
• stress
– our response to those stressors
• causes/effects of acute and chronic stress
– acute stress – occurs in response to an immediate
perceived threat
– stress can be caused by just thinking
– chronic stress – stress that goes on continuously—may
lead to persistent autonomic nervous system arousal
• breakdown of immune system
Chapter Summary
• Discuss the nature and basic function of the
nervous system.
• Explain what neurons are and how they
process information.
• Identify the brain’s levels and structures and
summarize the function of those structures.
• Identify the endocrine system and describe
how it affects behavior.
Chapter Summary
• Describe the brain’s capacity for recovery and
repair.
• Explain how genetics increases understanding
of behavior.
• Describe the role of the biological foundations
of human psychology in the body’s stress
response.
Chapter Summary
• The Nervous System
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structure and function of the nervous systems
structure of a neruon
electrochemical communication
neurotransmitters and their effects
• Brain: Structure and Function
– brain imaging techniques
– hindbrain, midbrain, forebrain
– cerebral lobes and functions
Chapter Summary
• Brain Damage and Plasticity
– collateral sprouting, substitution of function,
neurogenesis, brain tissue grafts
• Genetics and Behavior
– “genes v. environment” and adoption studies
• Biological Foundations & Health and Wellness
– acute and chronic stress